Enteral feeding tubes in one form or another have been used for a number of years to supply nutritional fluids to a patient. Typically, such devices consist of four parts or elements, namely, a flexible feeding tube for delivering nourishment to the patient, a semi-rigid stylet for positioning the feeding tube in the stomach or duodenum of the patient, a bolus tube section and weight for retaining the feeding tube in the stomach or duodenum of the patient and a connector on the proximal end of the feeding tube for attachment of the supply of nutritional fluid to the feeding tube.
A principal problem associated with feeding tubes is their proper placement within the patient. The feeding tube is preferably constructed of a soft and extremely flexible material so as to cause as little pain and trauma to the patient as possible during insertion of the feeding tube and to increase the length of time a patient may be intubated. To enable the insertion of a flexible feeding tube through the nose and down into the stomach or duodenum of a patient, the rigidity of the tube must be increased during he intubation procedure. One commonly used approach to increase the rigidity of the feeding tube during intubation is by removably mounting a semi-rigid stylet in the feeding tube. This approach allows the user to use a flexible feeding tube to provide nutritional fluid to a patient while increasing the rigidity of the feeding tube during the insertion of the feeding tube into the patient. Once the feeding tube has been properly positioned in the patient, the stylet is removed from the feeding tube so that the feeding tube will be flexible during the time it is within the patient.
Early stylets consisted of an elongate wire having a solid plug member on the proximal end thereof to allow the stylet to be removably retained in the connector on the proximal end of the feeding tube and an enlarged ball-shaped stylet tip formed on the distal end of the stylet wire. The early stylets were generally disfavored because the stylet tip would occasionally pierce the feeding tube and traumatize the patient tissues as the feeding tube was being inserted into the patient. On other occasions, the stylet tip would pass through the side holes of the feeding tube and traumatize the patient tissues as the feeding tube was being inserted into the patient.
One approach to solving this problem has been to increase the diameter of the stylet tip so that it is less likely to pierce the feeding tube and will not pass through the side holes of the feeding tube. One example of this approach is U.S. Pat. No. 4,659,328 granted to Potter et al which discloses the use of a helically coiled small diameter wire on the distal end of the stylet wire. As described in the Potter et al patent, the coils of the wire are oriented transversely to the longitudinal axis of the stylet wire and are dimensioned such that the stylet tip is prevented from exiting the feeding tube by passing through the side holes in the feeding tube. This patent also discloses that the length of the stylet wire is chosen so that the stylet tip is compressed against the end wall of the feeding tube when the stylet is inserted into the feeding tube. A similar stylet having a small diameter wire stylet tip is disclosed in U.S. Pat. No. 4,636,200 granted to Vaillancourt which is assigned to Sherwood Medical Company and incorporated herein by reference as if fully set forth herein. U.S. Pat. No. 4,496,347 granted to MacLean et al also discloses an enlarged wire stylet tip which is described as being sized such that the stylet tip is prevented from piercing the feeding tube or passing through a side hole in the feeding tube. The stylet of Maclean et al consists of a single or stranded wire which is bent in half and then twisted about itself to form a double helix and so that the stylet tip is an elongated wire loop of a variable size.
Yet another approach is illustrated in FIG. 1 where the stylet is formed of a twisted wire and includes a PVC sleeve bonded to the distal end of the stylet wire. As illustrated, the sleeve extends only slightly beyond the distal end of the stylet wire and functions primarily to prevent the stylet wire from fraying and possibly piercing the feeding tube. The stylet wire and sleeve are sized such that the distal end of the sleeve extends to a location proximally of the side holes of the bolus tube when the stylet hub is placed in the connector on the proximal end of the feeding tube.
The preferred stylet is simple and economical to manufacture and will not cause excessive trauma to the patient if the stylet tip should inadvertently pierce the feeding tube or extend through the side holes of the feeding tube. The stylet tips disclosed by Potter et al and Vaillancourt, as described above, are relatively complex to manufacture and the use of a wire stylet tip may cause excessive trauma to the patient if the stylet tip pierces the feeding tube or is deflected to extend through the side holes of the feeding tube. The stylet tip disclosed by MacLean et al, as described above, is relatively simple to manufacture but is easily deformed and may cause excess trauma to the patient if the stylet tip pierces the feeding tube or is deflected to extend through the side holes of the feeding tube. The approach illustrated in FIG. 1 is simple to manufacture but forms a relatively rigid stylet tip which will not adequately protect the tissues of the patient from trauma. The rigidity of this prior art stylet tip is due to the presence of the stylet wire within substantially the entire length of the sleeve and therefore, the stylet tip of this device may cause excessive trauma to the tissues of the patient if the relatively rigid stylet tip inadvertently pierces the feeding tube. Additionally, by terminating the stylet tip near the proximal end of the bolus tube section, there is an increased likelihood that the feeding tube will bend or possibly even separate at the junction of the feeding tube and the bolus tube section.
Although the above described stylets purportedly will not pierce the feeding tube or pass through the side holes of the feeding tube, many hospitals still require that physicians intubate their own patients due to the likelihood that the wire stylet tip may pierce the feeding tube or extend through the side holes of the feeding tube if the feeding tube and stylet are improperly inserted into the patient. The use of a wire or rigid stylet tip in the present devices will significantly increase the severity of the injury to the patient if the feeding tube is improperly inserted into the patient.
Therefore, a need remains for a stylet which is simple and inexpensive to manufacture and will not pierce the feeding tube and which will not cause excessive trauma to the tissues of the patient if it is inadvertently manipulated to extend through the side holes of the feeding tube.